Yea, if you're going solo, be careful when planing mountain roads. Google may say the route is only 100 km, but it it's shapes like a small intestine, then expect to tripple the time it takes. Not just because of the 1st. gear turns, but to give you time for those unbelievable places to stop and take it all in.
We crossed Mallorca last November (no bike, just a Mini convertible) taking to northern clift road that hugs the costline. Normally it takes about 3-4 hours to cross the island via the highway, this road took two days! Worth every moment!
As scary as a non guided trip may seem, it's actually the most rewarding. We did three days in the Bavarian alps on a BMW St, no guide, no real map, and a disfunctional GPS. The place is so beautiful, you just can't go wrong no matter where you turn.
In the mountain areas, there is typically only one way to get from point A to point B. A very strange concept coming form the NorthEast, but easy to figure out. When you get there, you'll see why. Short of a massive tunnel, there is no where else to make a road!
One thing I would advise is that if you're a newer or timid rider, don't try riding in Europe. The skill level you need is much higher, and all of the other drivers will expect it.